diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-includes/class-wp-simplepie-sanitize-kses.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/class-wp-simplepie-sanitize-kses.php	Mon Oct 14 17:39:30 2019 +0200
@@ -0,0 +1,58 @@
+<?php
+/**
+ * Feed API: WP_SimplePie_Sanitize_KSES class
+ *
+ * @package WordPress
+ * @subpackage Feed
+ * @since 4.7.0
+ */
+
+/**
+ * Core class used to implement SimpliePie feed sanitization.
+ *
+ * Extends the SimplePie_Sanitize class to use KSES, because
+ * we cannot universally count on DOMDocument being available.
+ *
+ * @since 3.5.0
+ *
+ * @see SimplePie_Sanitize
+ */
+class WP_SimplePie_Sanitize_KSES extends SimplePie_Sanitize {
+
+	/**
+	 * WordPress SimplePie sanitization using KSES.
+	 *
+	 * Sanitizes the incoming data, to ensure that it matches the type of data expected, using KSES.
+	 *
+	 * @since 3.5.0
+	 *
+	 * @param mixed   $data The data that needs to be sanitized.
+	 * @param integer $type The type of data that it's supposed to be.
+	 * @param string  $base Optional. The `xml:base` value to use when converting relative
+	 *                      URLs to absolute ones. Default empty.
+	 * @return mixed Sanitized data.
+	 */
+	public function sanitize( $data, $type, $base = '' ) {
+		$data = trim( $data );
+		if ( $type & SIMPLEPIE_CONSTRUCT_MAYBE_HTML ) {
+			if (preg_match('/(&(#(x[0-9a-fA-F]+|[0-9]+)|[a-zA-Z0-9]+)|<\/[A-Za-z][^\x09\x0A\x0B\x0C\x0D\x20\x2F\x3E]*' . SIMPLEPIE_PCRE_HTML_ATTRIBUTE . '>)/', $data)) {
+				$type |= SIMPLEPIE_CONSTRUCT_HTML;
+			}
+			else {
+				$type |= SIMPLEPIE_CONSTRUCT_TEXT;
+			}
+		}
+		if ( $type & SIMPLEPIE_CONSTRUCT_BASE64 ) {
+			$data = base64_decode( $data );
+		}
+		if ( $type & ( SIMPLEPIE_CONSTRUCT_HTML | SIMPLEPIE_CONSTRUCT_XHTML ) ) {
+			$data = wp_kses_post( $data );
+			if ( $this->output_encoding !== 'UTF-8' ) {
+				$data = $this->registry->call( 'Misc', 'change_encoding', array( $data, 'UTF-8', $this->output_encoding ) );
+			}
+			return $data;
+		} else {
+			return parent::sanitize( $data, $type, $base );
+		}
+	}
+}